In earthworking machines such as wheel loaders, a work implement such as a bucket is mounted to the front end of a machine by a linkage arrangement that permits the manipulation of the bucket to excavate and load material in a variety of ways. The bucket is mounted to the machine by one or more lift arms and is lifted in a vertical plane by a pair of hydraulic cylinders that extend between the lift arm and the machine. A portion of the linkage arrangement usually incorporates a combination of links that connect an upper portion of the bucket to another hydraulic cylinder that when actuated, will pivot the bucket with respect to the lift arm. With this type of linkage, material may be loaded into the bucket under motive force of the vehicle and elevated by the lift arms. The material may then be dumped into a nearby truck or it may be transported in the bucket to be deposited at a remote site.
During the operation of the wheel loader, the bucket and the linkage arrangement is subjected to varying degrees of force, some of rather severe magnitude. It is therefore critical that each component of the linkage arrangement is of sufficient size and is sufficiently configured to withstand the forces encountered during operation. It must be noted however, that while the size and configuration of the respective components of a linkage arrangement are critical, so is the weight of the components. It is therefore very desirable to provide a linkage arrangement that is not only strong enough to withstand severe loading but will not add unduly to the overall weight of the machine and thereby detract from the performance capabilities of the machine.
In some instances, linkage arrangements have been known to utilized a single lift arm instead of a pair of lift arms that normally extend between the bucket and the machine. One such design is disclosed in U.S. Pat. 4,768,917 issued to Anthony L. Garman on Sep. 6, 1988. In this design the tilting arrangement utilizes a tilt lever that is an elongate member having three distinct areas of connection that will be subjected to the majority of the loads during the operation of the linkage. These areas of loading occur at the connection points between the tilt lever and the tilt cylinder, the tilt links and the bucket. Because these areas are distinct and are spread out over the length of the tilt lever, the mass of the tilt lever must be increased in each of these locations to accommodate the loading that will be applied to the linkage at each of these areas. While this is not necessarily a significant disadvantage on wheel loaders that are relatively small, the increase in mass in each of the three areas of connection will result in a dramatic increase in weight when utilized on larger vehicles. The increase in weight not only detracts from the performance capabilities of the machine, it also dramatically increases the cost of the components. Another disadvantage that is apparent in the design is the necessity to utilize two tilt inks on opposite sides of the tilt lever. This not only increases the overall weight of the linkage but also increases the number of components.
The present invention is directed to overcoming one or more of the problems as set forth above.